Electrical translating apparatus



Dec. 31, 1929. L. O.- GRONDAHL 3 ELECTRICAL TRANSLATING APPARATUS FiledJan. 8. 1923 II R . V/IIIIII mvemon:

,BY w arugu- #4,. ATTORNEY Patented Dec. 31, 1929 UNITED STATES PATENTOFFICE LABS O. GRONDAHL, F PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO THEUNION SWITCH & SIGNAL COMPANY, OF SWISSVALE, PENNSYLVANIA, A CORPORATIONOF PENNSYLVANIA ELECTRICAL TRANSLATING APPARATUS Applicationfiledlanuary 8, 1923. Serial No. 611,286.

My invention relates to electrical translating apparatus.

I will describe several forms of apparatus embodying my invention, andwill then point out the novel features thereof in claims.

In the accompanying drawing, Fig. 1 is a view, partly diagrammatic andpartly in cross-section, showing one form of translating apparatusembodying my invention.

Fig. 8 is a view similar to Fig. 2 but showing another modification of aportion of the translating device of Fig. 1.

Similar reference characters refer to similar parts in each of theviews.

Referring first to Fig. 1, the apparatus includes a translating device,shown here as functioning as a relay, which device is designated as awhole by the reference character.

It. This device comprises a glass bulb 7, within which is a heatingelement H. This element, as here shown, is in the form of a fine wirefilament the terminals of which are connected with contacts 9 and 12.Surrounding the bulb 7 is an inner. tube-shaped electrode 10 ofelectro-conductive material so formed as to obstruct only a portion ofthe heat rays emitted by the heating element H. This electrode may be inthe form of a perforated metallic tube, such as a grid or a metallicgauze, or it may be of thin sheet metal which has sufiicient crosssection area to carry the secondary current and which at the same timeis capable of transmitting a considerable portion ofthe heat emitted bythe filament H. As shown in the drawing this electrode is inthe form ofa grid."- Surrounding the electrode 10 is an envelope E of a substancehaving the characteristic of vary ing in electrical resistance inresponse to temperature variations, and which I will term thethermo-sensitive substance. This substance preferably has a highnegative coeiiicient, so that its electrical resistance decreases as itstemperature increases, and rises again, upon cooling, to substantiallyits original value. Asexamples, this substance may be cupric oxide,cuprous oxide, silver selenide, silver sulphide, carborundum paste,alundum cement, a fusion of copper and mica, the rare earth oxides usedin the Nernst lamp filament, and probably a number of other substances.The thermo-sensitive substance E is surrounded by a second or outertube-shaped electrode 11, also of electro-conduct-ive material. Theinner electrode 10 is electrically connected with a contact 9 by a wire13, and the outer electrode 11 is connected by a wire 14 with a contact12.

The heating element H is included in a primary circuit which comprises asource of current and means for controlling or modifying the flow ofcurrent in the heating element. As here shown, the primary circuitpasses from a battery B, through wire 21, switch S, wire 22, contact 20,contact 9, heating element H, contact 12, contact 19, an wire 23 tobattery B. p 1

The secondary circuit comprises a source of current which as here shownis a battery B and an electromesponsive device which as here shown is anelectric lamp L. The secondary circuit in the form shown in Fig. 1passes from the battery B through wire 24, contact 19, contact 12, wire14, outer electrode 11, thermo-sensitive substance E, inner electrode10, wire 13, contact 9, contact 20, wire 25 and lamp L to battery B".

As here shown, the contacts 9 and 12 are includedin a lug 8 which isattached to one end of the b11187, whereas the contacts 9 and 12 areincluded in a similar plug 8 which is attached to the other end of thebulb. The contacts 19 and 20 are in the form of s ring contact fingersattached to a base 2 as s own in Fig. 7 and the outside wires of theprimary and secondary circuits are connected with these fingers. It willbe seen that with this construction the bulb 7 can readily be a plied toand removed from the hose 2, an that when it is in place onthe base thecontact members 12 and 19,20 and 9,12 and 19, and 20 and 9 are all inelectrical engagement.

The operation of the apparatus shown in Fig. 1 is as follows:

When the switch S is open, as shown in full lines in the drawing, thesupply of current to the heating element His discontinued, so that thiselement and the thermo-sensitive substance E are comparatively cool.Under this condition the resistance of the thermosensitive substance Eis so high that the current, it any, which flows in the secondarycircuit from battery B is not sufficient to light the lamp L. When,however, the switch S is closed so that current is supplied to theheating element H from the primary battery ll,

this element becomes heated and in turn raises the temperature of thethermo-sensitive substance E. The resistance of the substance E is thenreduced to such value that the current which flows in the secondarycircuit from battery'B? is of sufficient magnitude to light the lamp L.When switch S is again opened the heating element H and thethermo-sensitive element E again become cool, so that lamp L becomesextinguished.

When the inner electrode 10 is in the form of a perforated conductor,such as gauze or a grid, this electrode will not be in electricalcontact with all points on the inner surface of the thermo-sensitivesubstance E, and so the efiiciency of the device will not be maximum. Ifdesirable, the efficiency may be increased by t he modification shown inFig. 2, wherein a tube-like member 15 of heat-conductive,electro-conductive material, such as thin gold leaf, is interposedbetween the electrode 10 and the thermo-sensitive substance E. This tubeor sleeve 15, which may be termed an auxiliary inner electrode, will ineffect place the main inner electrode 10 in electrical contact withsubstantially the entire in ner surface E, and so will increase theefliciency of the device to a maximum;

In Figsfl and '2 the inner electrode 10 is perforated to secure thedesired thermal conductivity. The same result may be accomplished bymaking this electrode thin and unperforated, and blackening the innersurface, that is, the surface next to the heating element, so that thissurface becomes a good heat-absorbing surface. This modification isillustrated in Fig. 8.

I have found that when certain thermo-sensitive substances are operatedin air, a grad ual change occurs in the nature of the substance and soin its characteristics. For example, cuprous oxide gradually changes tocupric oxide,-with the result that a change occurs in thecharacteristics of a device in which this substance is employed. Thischange may be avoided by operating the substances in vacuo or in a gashaving no effect on the substance. In Fig. 3 Ihave shown a device Rsobonstructed' as to permit operation of the thermo-sensitive substanceunder either of these conditions. In this view, the electrodes 10 and11, with the thermo-sensitive substance E betweenthem, are locatedwithinthe bulb 7 instead of on the outer surface of the bulb as in Fig. 1.These members may be supported in any suitable manner, as for example,by

on the thermo-sensitive substance E, such forexample as nitrogen, argonor helium. A small amount of oxygen may be added to this gas to preventdischarge of oxygen from the thermo-sensitive substance E when thedevice is first put into service.

' It is, of course, obvious that the inner electrode 10 and thethermo-sensitive substance E in Fig. 3 may, if desirable, be moreintimately connected by an auxiliary inner electrode as in Fig. 2.

The device R of Fig. 3 may be substituted for the device R in theapparatus shown in Fig. 1 and the operation of the apparatus will be asexplained hereinbefore.

Referring now to Fig. 4, the device R shown herein comprises a tube 7provided with terminal plugs 8 and 8 as in the preceding views. Mountedin the tube is a heating element H in the form 'of a wire of suitablematerial such as nichrome, the terminals of which are connected with thetwo-terminals respectively of plug 8." This heating elementpassesthrougha bead or-globule E of thermo-sensitive substance. Alsoembedded V in the bead E are two electrodes .10 and 11*" which as hereshown are in the form of wires and which are connecterhwith-the twocontacts 9 and 12%, respectively of plug 8. The

electrodes are spaced from each other and from the heating element H bythe bead E.

The-bead, electrodes and heating element -,ping the heated portions ofthe electrodes into a powdered thermo-sensitive substance so that .asmall portion of the substance adheres to the electrodes, and repeatintheprocess until a suflicient quantity of the thermo-sensitive substancehas adhered to the electrodes to form a, bead injwhich they areembedded. The heating element H may be passed through this bead whilethe latter is still hot. As a modification ofthis process, the twoelectrodes and the heating element may all be clamped inproper spacedrelation an the bead applied thereto as before. Still Fig. 1, and theoperation of the apparatus will be as explained hereinbefore.

Referring now to Fig. 5, the device R illus' .trated herein comprises aheating element H and two electrodes 10 and 11, all in the form ofwires. As an example, the electrodes may be of nickel, plated withcopper. These electrodes are first twisted together or intertwined toform two helical conductors with the turns of one alternating with theturns of the other, and the heating element H is then 1 twisted aroundthe electrodes. The whole unit is then heated in a furnace to transformthe copper coating into copper oxide which is a thermo-sensitivesubstance, so that each turn of each electrode is separated from theadjacent turns of the other electrode by a coating of this substance. Orto express the same thing in a difierent way, the

intertwined electrodes are embedded in thermo-sensitive substance. Ofcourse if desired the electrodes may be of copper wire, in which casethe copper plating is unnecessary. This form of the device may be sodesigned as to carry relatively heavy currents.

The device R illustrated in Fig. 5, may

J be substituted for device R in the apparatus shown in Fig. 1, and theoperation of this apparatus will then be the same as before.

Referring now to Fig. 6, device R comprises aglass bulb 7 provided withtwo plugs 8 and 8as in the preceding views. In Fig. 6, however, theelectrodes 10 and 11 are in the form of wires or strips which are placedside by side, and the heating element H is then wrapped around theseelectrodes. The

. electrodes ma be of copper, or they may be of other suita le metal,such as nickel, plated with copper. In either case, after the parts areassembled the unit is baked in a furnace to convert the copper surfacesof the electrodes into copper oxide so that these elec- .trodes areseparated from each other and from the heating element H by athermosensitive substance. After this baking is finished, the parts aremounted in the tube 7 and connected with the plug contacts as shown.

The device shown in Fig. 6 may be substituted for the device R in Fig.1, and the apparatus shown in Fig. 1 will operate as explainedhereinbefore. s y In each form of the apparatus the parts are soproportioned that the changes in the conductivit of the thermo-sensitivesubstance areuealmostentirely to changes in thetemperature of theheatlnelement H,

and are sensibly independent 0 temperature -to receive the pluvariations due to the secondary current car"- ried by thethermo-sensitive substance, so that under'no clrcumstances can theheated con-- effect in determining the temperature and so theconductivity of the thermo-sensitive substance. In so far as dimensionsenter lnto stance preferably has a comparatively short path ofcomparatively large area for the secondary current. The properproportioning also includes, of course, the voltage applied to thesecondary circuit.

One important feature of the devices shown in Figs. 1, 2 and 3 is thetube-like form of the thermo-sensitive substance E, whereby thissubstance is exposed to a very large proportion of the heat emitted bythe heating element H.

Another important feature of the devices shown in the presentapplication is the provision of the two terminal plugs 8 and 8 which areintegral with the body of the device. The primary or controlling circuitwith which the heating element H is connected includes the springcontact fingers designed. 8, and the secondary or controlled circuit-1nwhich the electrodes 10 and 11 are includedterminates in the springcontact fingers which are designed to receive the plug 8. Thisconstruction greatly facilitates the insertion of the device in the apparatus with which it is associated as well as the removal of the devicetherefrom. The twoplugs 8 and 8* may be of different sizes; as shown inthe drawings, and the spring contact fingers at the two ends of the base2 may be diflerently spaced to correspond to the two plugs, in order toprevent wrong connection of the device in the circuits with. which it isassociated.

While I have in each instance shown the heating element as mounted in atube andprovided with terminals for attachment and detachment from acircuit, these features are not essential. Neither does the enclosureimply that the heating element is necessarily to be heated toincandescen'ce or enclosed in a vacuum or non-oxidizing atmosphere. Anvsuitable enameling may be substituted, and the devices are notnecessarily enclosed. -Where permanence is important it is desirablethat the thermo-sensitive substance be protected from chan e ofcharacter and for this purpose I pre er the. enclosed forms shown forthe reasons already stated. Also an incandescent filament forms aconvenient heating element where its resistance and temperature aresuited to the application to'be made and in such case a .vacuous orneutral gas enclosure is advantageous,but any heating'element giving asuitable rise of tempera- 75 this proportioning, the thermo-sensitivesubv ture for any particular application may be used and it may or maynot be enclosed and may or may not be provided with fixed terminals.Also the degree to which the temperature of the 'thermo-sensitivesubstance is to be raised and lowered depends upon the nature of thesubstance selected, the change of resistance desired in the secondarycircuit or circuits controlled thereby and in some cases u on-thecurrent which is to flow therethrou While I have shown only a singlecircuit controlled by one thermo-sensitive unit, it will be readily seenthat more than one may:

be controlled and-also that a single heating element may act upon morethan one thermosensitive device.

Also'while I have shown two batteriesin Fig. 1 it will be understoodthat in many cases a single battery may be employed and in generalthecircuits may be varied to suit conditions without departing from myinvention.

While in general the device will, as stated,

he so proportioned that under no circmstances of its use can thesecondary current continue the heating of the thermo-sensitive substanceto the operative temperature it may at times be desirable to constructdevices so that the conductive condition once established will continueuntil the circuit is interrupted. I therefore do not limit myself inthis re ard.

Although I have herein shown an described only certain forms ofapparatus embodying my invention, it is understood that various changesand modifications may be made therein within the scope of the appended.claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is: i 1

1. A thermo-sensitive device comprising a thermo-sensitive substance,and two helical conductors embedded in said substance with the turns ofone conductor alternating with the turns of the other but spaced by thethermosensitive substance, and a heating element intertwined with saidconductors.

Y 2. A thermo sensitive device comprising two helical conductorsarranged so that the turns of one alternate with the turns of the other,a coating of thermo-sensitive substance on each conductor, and a'heatingelement intertwined with said conductors.

In testimony whereof I'aflix my signature.

LABS O. GRONDAHL.

